Landon Donovan played for Everton while on loan from LA Galaxy. Photograph: Alex Livesey/Getty Images

Jürgen Klinsmann has told his son to apologise to Landon Donovan for a “disrespectful” tweet after the striker was left out of the United States World Cup squad.

Jonathan Klinsmann, a goalkeeper with the US Under-18s, followed Thursday’s squad announcement by tweeting: “HAHAHAHAHAHAH DONOVAN HAHAHAHAA I DIDNT EVEN NOTICE UNTIL MY PHONE NOTIFIED ME” followed by four emoticons with tears and another “HAHA”. The account was quickly deleted.

“Hugely disappointed. I called him right away,” the US coach, Klinsmann Sr, said on Friday. “He realised just a few minutes after that what he’s done. He came out of school kind of fooling around with his classmates and they just went off on Twitter, not being aware that he’s actually followed on Twitter.”

“He has a huge admiration for Landon. He’s actually a big fan of him since many, many years. He has his jersey in his room,” the coach continued. “He realised what he’s done, so he was devastated yesterday. And obviously as a father you put him in line and he owes him a huge, huge apology. That was highly disrespectful and I think he got his biggest social media lesson that he could imagine.”

The dropping of Donovan came as a huge shock. The Los Angeles Galaxy striker, 32, who played for Everton, Bayer Leverkusen and Bayern Munich in Europe, took part in the last three World Cups, scoring five times. He has 156 caps and has scored 57 goals, a national record.

Analysis

Graham Parker: Jurgen Klinsmann's shock decision gave his strongest indication yet that form, not reputation, will determine his team — but axing the USA's highest scoring World Cup player is a big risk